Pressure sensitive adhesive tapes are provided with release coatings to prevent roll blocking or adhesive transfer from the pressure-sensitive adhesive coated side of a tape backing that is wound convolutely upon itself to the non-coated side of the tape backing. One form of release coating is the low adhesion backsize or LAB. One particular form of tape backing that is preferred for use in medical applications as well as other applications is made from a nonwoven fabric web.
Nonwoven tape backings are generally made by first forming a web and applying a binder to the web to adhere the fibers one to another at their crossing points. The thus prepared web is then heated to drive out the organic solvent or water from which the binder was applied, and the fabric is then transported to the next process step. In a second step, a release coating is applied to the web and the backing is again heated to drive out the organic solvent or water. Typically, the release coating is applied from a volatile solvent for easier control of the rate of migration of the release coating through the web backing. A third separate step is then performed wherein an adhesive is applied to the uncoated side of the web. The web is again heated to drive out the organic solvent or water from which the adhesive was applied and is then wound into a roll for transportation to the slitter, where individual size rolls of tape are separated from the master roll.
Each of the above separate heating steps results in the expenditure of substantial energy and time. Additionally, the application of the binder, release coating and adhesive from solvents results in high material costs and raises pollution concerns when the solvent volatilizes and is lost to the atmosphere.